Field of the Invention
The present invention relates to a low-temperature storage, and more particularly to a technique of reducing power consumption while maintaining quality of preservation of an item to be refrigerated.
Description of the Related Art
Japanese Patent Application Laid-Open Publication No. 2008-45790 discloses a low-temperature storage that includes a refrigerant circuit, a main body configured with a thermally insulated casing, a storage chamber to be cooled by a cooling device, and a blower for circulating cold air, wherein the blower is operated to forcibly circulate cold air, cooled by the endothermic action of a cooler, in the storage chamber, thereby cooling the interior of the storage chamber to a predetermined temperature. In Japanese Patent Application Laid-Open Publication No. 5-322415, a partition wall is provided on the cold air intake side of the cold-air circulation blower so as to partition a chamber into that on the storage chamber and that on the cold air intake side, a temperature sensor for detecting the internal temperature is provided in a space formed by the partition wall, and based on this, an internal temperature is displayed.
In a low-temperature storage such as a refrigerator, a freezer, an increase in set temperature leads to a reduction in load on a refrigerating machine (e.g., reduction in load on a compression machine (compressor)), thereby being able to reduce power consumption. However, in order to maintain the quality of preservation of the item to be refrigerated, practically, there is a tendency to set the set temperature at a temperature lower than that actually required, allowing an increase in the internal temperature when the door is opened/closed. In particular, when the item to be refrigerated is a medical product, a biological sample, etc., it is often the case that opening/closing for taking out the item to be refrigerated and opening/closing for returning the item to be refrigerated into the device are performed at short intervals, such as right after the door is opened and closed to take out a container storing the above items, the door is opened and closed to return the container into the device. In such use environment, particularly, the necessity to maintain the quality of preservation is great, resulting in a tendency to set the set temperature lower.
Whereas, it is normal that the frequency of opening/closing of the door varies with the time of day, or from day to day. For example, in a household refrigerator which is used to refrigerate food and the like, the frequency of opening/closing of the door during the evening hours is low as compared with that during the daytime hours. The door opening/closing frequency of a low-temperature storage provided in a research facility or healthcare facility which is used to refrigerate a medical product, a biological sample, or the like is extremely decreased on holidays and during a long vacation as compared to weekdays. Thus, when the set temperature is set lower so as to maintain the quality of preservation of the item to be refrigerated, the internal temperature is unnecessarily maintained at a low temperature even during a period of low frequency of opening/closing, thereby needlessly consuming power.